<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录页面-盒子模型</title>
  <style>

      .login-box{
           width: 450px;
           border: 1px solid;
            margin-left: 400px;
            margin-top: 400px;
            padding: 8px;
      }
      .row {

      }
  </style>
</head>
<body>
   <div class="login-box">
     <div class="row">
           用户名: <input type="text">
     </div>
     <div class="row">
         密码: <input type="text">
     </div>
     <div class="row">
         <button>登录</button>
     </div>

   </div>


</body>
</html>